Predetermined parameters for a selection of popular machines are included in COMMENTs at the top of SPECFUN programs. Conversion of a program for a particular machine is then a simple matter of determining the proper parameter values, either from the given values or through computations based upon the definitions supplied, and inserting them in DATA statements in the routine. The MACHAR program computes machine parameters from a built-in model of the arithmetic system.

All precision-dependent source statements are duplicated. Statements peculiar to single-precision contain 'CS' in the first two characters, while their immediately following double-precision counterparts contain 'CD'. A precision-specific source is produced by global editing changes of the characters 'CS' or 'CD' to blanks in the first two characters of the appropriate source statements.